Process for colouring elements made of polymeric material, in particular yarns selectively produced in polyethylene (pe), in ultra high molecular weight polyethylene (uhmw-pe) and derivatives thereof such as hshm-pe

A liquid colorant for colouring elements (10) made of polymeric material, in particular yarns selectively produced in polyethylene (PE), in ultra high molecular weight polyethylene (UHMW-PE), in high strength and high modulus polyethylene (HSHM-PE), characterized in that it comprises:

• a mixture of water (2), pigments (3), additives (4) comprising a buffer agent (5), an equalizing agent (6) and a dispersing agent (7);
• said pigments (3) being chosen from anthraquinone colorants, azo colorants, inks for the textile industry, and being provided in quantities between 0.2% and 15% of the weight of said elements (10) to be coloured;
• said buffer agent (5) selectively including acetic acid, formic acid, borax and being provided in quantities between 2.6 and 0.2 grams for each litre of said water (2);
• said equalizing agent (6) selectively including substances based on polyglycol ether, on ethoxylated carboxylic acid and aryl sulphonate, on aromatic esters, and being provided in quantities between 4.0 and 0.02 grams for each litre of said water (2) and said dispersing agent (7) being defined by anionic agents present in quantities between 4.0 and 0.02 grams for each litre of said water (2).